1/4-16 ACME Thread Dimensions

Basic information

Designation

1/4-16 ACME

Thread system

ACME

Series

acme

Standard

ASME B1.5

Basic profile

ACME basic profile

Flank angle

29°

Dimensions

Major diameter

0.25 in / 6.35 mm

Pitch (metric equivalent)

1.587 mm

Threads per inch

16

Pitch diameter

0.2189 in / 5.56 mm

Minor diameter (external)

0.1673 in / 4.25 mm

Minor diameter (internal)

0.1673 in / 4.25 mm

Thread depth

0.0413 in / 1.048 mm

Recommended tap drill

Ø 0.1875 in / 4.762 mm

These figures follow the ACME basic profile of ASME B1.5. A 29° ACME profile has a thread height of h = 0.5 × P + 0.01 in, the 0.01 in being the ACME clearance rather than a rounding: the pitch diameter is d₂ = d − 0.5 × P, the external minor diameter is d₃ = d − 2h, and the internal minor diameter is D₁ = d − P − 0.02 in. The recommended tap drill is given as nominal diameter minus pitch, which here sits 0.02 in above the basic internal minor diameter — that 0.02 in is the ACME crest clearance — so it is a starting point rather than a cutting recommendation.

No specification in this database uses 1/4-16 ACME. Power threads are not fastener threads — they are found on lead screws, jacks and vice screws, so no bolt or nut in this catalogue is made in this form. The geometry above is what a machinist needs to cut it.

Neighbouring sizes in ACME.